A gut feeling: how your gut and brain changes your risk and time preferences

Recent research has shown that the gut microbiota can influence the interaction between the central and the enteric nervous systems via the gut-brain axis (GBA). Animal models and human neuroimaging studies have revealed that changes in the gut microbiota affect neural activity in brain regions linked to basic emotional and cognitive processes. Whether the gut microbiota also affect human decision-making and, more specifically, risk and time preferences, however, remains largely unknown. Here, we examine the role of the gut-brain axis in decision-making in the face of risk and intertemporal choices. In a placebo-controlled double-blinded design, with two sessions separated by 28 days, during which participants received daily doses of probiotics (or a placebo), we investigate whether the prolonged and controlled intake of probiotics affects risk-taking behavior and intertemporal choices using incentivised economic tasks. We found a significant decrease in risk-taking behavior and an increase in future-oriented choices in the probiotics group as compared to the placebo group. These findings provided the first direct experimental evidence suggesting a potential functional role on the part of the microbiota-gut-brain axis in decision-making, creating a path for potential clinical applications and allowing for a better understanding of the underlying neural mechanisms of risk-taking behavior and intertemporal choices.

Intertemporal choice reflects value comparison rather than self-control: insights from confidence judgments

Intertemporal decision-making has long been assumed to measure self-control, with prominent theories treating choices of smaller, sooner rewards as failed attempts to override immediate temptation. If this view is correct, people should be more confident in their intertemporal decisions when they “successfully” delay gratification than when they do not. In two pre- registered experiments with built-in replication, adult participants (n=117) made monetary intertemporal choices and rated their confidence in having made the right decisions. Contrary to assumptions of the self-control account, confidence was not higher when participants chose delayed rewards. Rather, participants were more confident in their decisions when possible rewards were further apart in time-discounted subjective value, closer to the present, and larger in magnitude. Demonstrating metacognitive insight, participants were more confident in decisions that better aligned with their independent valuation of possible rewards. Decisions made with less confidence were more prone to changes-of-mind and more susceptible to a patience-enhancing manipulation. Together, our results establish that confidence in intertemporal choice tracks uncertainty in estimating and comparing the value of possible rewards – just as it does in decisions unrelated to self-control. Our findings challenge self- control views and instead cast intertemporal choice as a form of value-based decision-making about future possibilities.

Framing attributes in similarity judgments and intertemporal choices

Similarity models provide an alternative approach to intertemporal choice. Instead of calculating an overall value for options, decision makers compare the similarity of option attributes and make a decision based on similarity. Similarity judgments for reward amounts and time delays depend on both the numerical difference (x2-x1) and ratio (x1/x2) of quantitative values. Changing units of these attribute values (e.g., days vs. weeks) can alter the numerical difference while maintaining the ratio. For example, framing a pair of delays in the unit of weeks (1 vs. 2) or days (7 vs. 14) both result in a ratio of 1/2. Yet the numerical difference between the delays differs depending on the unit (1 for weeks and 7 for days). Here we had participants make similarity judgments and intertemporal choices with amounts framed as dollars or cents and delays framed as days or weeks. We predicted that they units of amounts and delays would influence similarity judgments which would then influence intertemporal choices. We found that participants judged amounts framed as cents as less similar than dollars, and this resulted in more patient intertemporal choices. Additionally, they judged delays framed as weeks as more similar than days, but the framing did not influence choice. These findings suggest that the units in which amounts and delays are framed can influence their similarity judgments, which can shape intertemporal choices. These unit effects may guide stakeholders in framing aspects of intertemporal choices in different units to nudge decision makers into either more impulsive or patient choice.

Are Impulsive Decisions Always Irrational? An Experimental Investigation of Impulsive Decisions in the Domains of Gains and Losses

Intertemporal choices are very prevalent in daily life, ranging from simple, mundane decisions to highly consequential decisions. In this context, thinking about the future and making sound decisions are crucial to promoting mental and physical health, as well as a financially sustainable lifestyle. In the present study, we set out to investigate some of the possible underlying mechanisms, such as cognitive factors and emotional states, that promote future-oriented decisions. In a cross-sectional experimental study, we used a gain and a loss version of an intertemporal monetary choices task. Our main behavioural result indicated that people are substantially more impulsive over smaller and sooner monetary losses compared to equivalent gains. In addition, for both decisional domains, significant individual difference predictors emerged, indicating that intertemporal choices are sensitive to the affective and cognitive parameters. By focusing on the cognitive and emotional individual factors that influence impulsive decisions, our study could constitute a building block for successful future intervention programs targeted at mental and physical health issues, including gambling behaviour.

The Differential Effects of Anger and Sadness on Intertemporal Choice: An ERP Study

Previous research has taken a valence-based approach to examine the carryover effects of incidental emotions on intertemporal choices. However, recent studies have begun to explore the effects of specific emotions on intertemporal choices. In this study, we investigated how anger and sadness influenced intertemporal choices using event-related potentials (ERPs). Behavioral results showed that, compared with neutral prime, anger prime was associated with more preference for delayed rewards, whereas sad prime did not change individuals’ choice preference. Specifically, anger prime yielded a shorter response time than sad prime for the difficult-to-select choices. ERP results found that, compared with neutral and sad primes, anger prime elicited larger P1 in the fronto-central and parietal areas, larger P2 in the fronto-central area, and larger P3 in the parietal area during the evaluation stage. These findings suggest that there are differential carryover effects of anger and sadness on intertemporal choice. This study provides enlightenment on the significance of understanding how incidental emotions affect individuals’ intertemporal choices.

Magnitude effect in intertemporal allocation tasks

Intertemporal choices are affected by both discount rate and utility curvature. We investigate how the two aspects of time preference are affected by the size of the total budget using an intertemporal allocation task. At the aggregate level as well as at the individual level, we find magnitude effects both on the discount rate and on intertemporal substitutability (i.e., utility curvature). Individuals are more patient when dealing with larger budgets and also regard larger budgets to be more fungible. The latter effect suggests that the degree of asset integration is increasing in the stake.

Temporal discounting when outcomes are experienced in the moment: Validation of a novel paradigm and comparison with a classic hypothetical intertemporal choice task

When faced with intertemporal choices, people typically devalue rewards available in the future compared to rewards more immediately available, a phenomenon known as temporal discounting. Decisions involving intertemporal choices arise daily, with critical impact on health and financial wellbeing. Although many such decisions are “experiential” in that they involve delays and rewards that are experienced in real-time and can inform subsequent choices, most studies have focused on intertemporal choices with hypothetical outcomes (or outcomes delivered after all decisions are made). The present study focused on experiential intertemporal choices. First, a novel intertemporal choice task was developed and validated, using delays experienced in real time and artistic photographs as consumable perceptual rewards. Second, performance on the experiential task was compared to performance on a classic intertemporal choice task with hypothetical outcomes. Involvement of distinct processes across tasks was probed by examining differential relations to state and trait anxiety. A two-parameter logistic function framework was proposed to fit indifference point data. This approach accounts for individual variability not only in the delay at which an individual switches from choosing the delayed to more immediate option, but also in the slope of that switch. Fit results indicated that the experiential task elicited temporal discounting, with effective trade-off between delay and perceptual reward. Comparison with the hypothetical intertemporal choice task suggested distinct mechanisms: first, temporal discounting across the two tasks was not correlated; and second, state and trait anxiety both were associated with choice behavior in the experiential task, albeit in distinct ways, whereas neither was significantly associated with choice behavior in the hypothetical task. The engagement of different processes in the experiential compared to hypothetical task may align with neural evidence for the recruitment of the hippocampus in animal but not in classic human intertemporal choice studies.

Time Preferences across Language Groups: Evidence on Intertemporal Choices from the Swiss Language Border*

Differences in patience across language groups have recently received increased attention in the literature. We provide evidence on this issue by measuring time preferences of French and German speakers from a bilingual municipality in Switzerland where institutions are shared and socioeconomic conditions are very similar across the two language groups. We find that French speakers are significantly more impatient than German speakers, and differences are particularly pronounced when payments in the present are involved. Estimates of preference parameters of a quasi-hyperbolic discounting model suggest significant differences in both present bias (β) and the long-run discount factor (δ) across language groups.

Gain-Loss Asymmetry in Delay and Effort Discounting of Different Amounts

Loss aversion entails the attribution of greater weight to losses than to equivalent gains. In terms of discounting, it is reflected in a higher rate for gains than for losses. Research on delay discounting indicates that such gain-loss asymmetry may depend on the amount of the outcome. In the current study, we address the question of how gains and losses are discounted in delay or effort conditions (physical or cognitive) across four outcome amounts. Our results replicate previous findings for intertemporal choices by showing that losses are discounted more slowly than gains, but only for smaller amounts, while there is no evidence of asymmetry in the evaluation for larger amounts. For physical effort discounting, we found an inverse asymmetry for the smallest amount tested (gains are discounted less steeply than losses), while such an effect is absent for larger amounts. Our results provide no support for the asymmetric evaluation of gains and losses for cognitive effort. Overall, our findings indicate that loss aversion may not be as pervasive as one might expect, at least when decisions are effort-based.